The present invention relates generally to oil condition sensors.
Today, many vehicles are equipped with oil life prediction algorithms or oil condition sensors that determine the life of the engine oil. Certain oil condition sensors determine the life of engine oil by quantitatively sensing an oil condition parameter, e.g., oil viscosity or oil acidity. Typically, these sensors allow a particular oil condition parameter to reach a certain threshold value, and then, indicate an oil change at least partially based upon reaching this threshold. For this group of sensors, it is easy to calculate the remaining oil life based on the fresh oil condition and the threshold value of the particular parameter, interpolate between these values, and translate the result into miles.
Other sensors do not quantitatively sense oil condition parameters, but rather look for a repeatable pattern of an oil condition parameter. When shown against elapsed operation time or miles driven, the oil condition parameter displays an oil condition parameter curve or trend. Such a trend would contain an event, e.g., a maximum or a minimum, which is known to correlate to a certain oil condition. The problem is to predict the remaining oil life in the time before this event happens in the trend.
One exemplary oil condition sensor trend, i.e., the output of the sensor plotted versus mileage or time, can be represented graphically by a parabolic curve opening downward. Specifically, over the life of the oil, its, e.g., conductivity, will increase to an apex and then decreasexe2x80x94closely resembling a parabolic curve. A control module connected to the sensor can determine when the oil should be changed based on the output of the sensor. For example, after a series of decreasing output values, the control module can send a signal to an output device to indicate to the driver that the oil should be changed soon. If the output values of the sensor continue to decrease, indicating further degradation of the oil condition, the control module can send another signal to an output device to indicate that the oil should be changed immediately.
Depending on the type of oil used, e.g., mineral, synthetic, etc., and the engine operating parameters, e.g., temperature, engine operating speed (rpm), etc., the sensors may indicate that the oil should be changed very early, e.g., four thousand miles driven, or very late, e.g., twenty thousand miles driven. Based on the oil condition parameter sensed, the control module connected to the sensor simply provides warnings, e.g., xe2x80x9cChange Oil Soonxe2x80x9d or xe2x80x9cChange Oil Now.xe2x80x9d However, in the case of an event related oil life sensor as described above, the control module is unable to provide a relatively accurate indication of the remaining oil life (ROL) before the warnings or therebetween. As such, a driver may not know whether the ROL of the engine oil is about to approach a critical level. Thus, if the driver is about to embark on a long trip in the vehicle, he or she may be unaware that the oil should be changed because the ROL is quite low, but not low enough to trigger, e.g., a xe2x80x9cChange Oil Soonxe2x80x9d warning. Moreover, without an indication of the ROL, the driver may choose to change the oil earlier than necessary based simply on the miles driven when, in fact, the engine oil may have a relatively high ROL.
The present invention has recognized these prior art drawbacks, and has provided the below-disclosed solutions to one or more of the prior art deficiencies.
A method for predicting remaining life of engine oil includes counting down a remaining oil life value toward a predetermined early warning threshold at a first countdown rate. Based on a first oil life event, the countdown rate is increased or decreased. Moreover, a continuous indication of the remaining oil life is provided using the countdown rate.
In a preferred embodiment, the method further includes counting down the remaining oil life value from the early warning threshold to a predetermined final warning threshold at a second countdown rate. Based on a second oil life event, the second countdown rate is increased or decreased. Preferably, any countdown rate or the actual ROL value can be adjusted in a positive or negative direction in response to the addition of fresh oil to the system or to contamination of the oil.
In another aspect of the present invention, a system for predicting remaining life of engine oil includes an engine and an oil pan that provides oil to the engine. An oil condition sensor communicates with oil in the oil pan. Moreover, a control module is electrically connected to the oil condition sensor. In this aspect, the control module includes a program for predicting remaining oil life of the engine oil based on signals from the sensor. Also, a display for presenting an indication of the remaining oil life is coupled to the control module.
In yet another aspect of the present invention a method for predicting remaining life of engine oil includes counting down a remaining oil life value toward a predetermined threshold at a countdown rate. In this aspect, the countdown rate is based on an oil life event. Moreover, a continuous indication of the remaining oil life is provided.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: